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A means-plus-function claim having a programmable computer or microprocessor programmed to perform an algorithm as its structure is invalid unless the specification discloses the algorithm or steps necessary to achieve the function

For a means-plus-function claim where the disclosed structure is a general purpose computer or general purpose microprocessor programmed to perform some function, the specification must disclose the algorithm, or steps, at least at a high level to meet the requirements of 35 U.S.C. 112, sixth paragraph.

Aristocrat Technologies sued International Game Technology (IGT) for infringement of U.S. Patent No. 6,093,102 (’102 patent), which is directed to an electronic slot machine. The U.S. District Court for the District of Nevada held that the claims of the Aristocrat patent were invalid for indefiniteness.

Claim 1 of the ’102 patent recited, among other limitations, a “game control means” that enabled a player to define an arrangement of slot machine symbols and receive a payout based on the player’s definition if the arrangement was displayed during the game.

The District Court held that the “control means” of claim 1 was a means-plus-function term invoking 35 U.S.C. 112, paragraph six, and that therefore the claim limitation had to be defined by the structure disclosed in the specification plus any equivalents. If the specification was found to be lacking in disclosing the necessary structure, (i.e., the structure needed to perform the claim limitation function), the claim as a whole would be found invalid for indefiniteness.

The District Court found that the specification did not disclose the needed structure to perform the functions of claim 1, and that, therefore, the claim was invalid for indefiniteness.

Aristocrat argued that the structure was a standard microprocessor-based gaming machine with “appropriate programming.” (The ’102 patent states only that, “it is to be understood that it is within the capabilities of the noninventive worker in the art to introduce the methodology on any standard microprocessor based gaming machine by means of appropriate programming.” This is, however, the only text of the ’102 patent that mentions “programming.”)

The District Court found that the specification lacked “guidance to determine the meaning of ‘standard microprocessor’ or ‘appropriate programming.’” Thus, the District Court held that “[m]erely stating that a standard microprocessor is the structure without more is not sufficient.” Additionally, the District Court held that there was no link between the asserted structure and any of the claimed functions provided within the specification. The specification provided no step-by-step process or algorithm, other than its statement that “appropriate programming” was required.

The Federal Circuit affirmed the District Court’s holdings and its explanation that “in a meansplus- function claim in which the disclosed structure is a computer or a micro-processor programmed to carry out an algorithm, a corresponding structure must be a specific algorithm disclosed in the specification, rather than merely ‘an algorithm executed by a computer.’”

The Federal Circuit noted that, “[i]n cases involving a computer-implemented invention in which the inventor has invoked means-plusfunction claiming, [the Federal Circuit] has consistently required that the structure disclosed in the specification be more than simply a general purpose computer or microprocessor.” A claim of a means for performing a function where only a general purpose computer is disclosed as the structure is therefore considered a purely functional claim. The functional claim language did not meet the standard of 35 U.S.C. 112, paragraph six, because the claim was not sufficiently limited in scope to “the corresponding structure, material, or acts” that performed the function.

The Federal Circuit restated its rationale from In re Alappat, 33 F.3d 1526, 1545 (Fed. Cir. 1994), that “a general purpose computer programmed to carry out a particular algorithm creates a ‘new machine’ because the general purpose computer ‘in effect becomes a special purpose computer once it is programmed to perform particular functions pursuant to instructions from program software.’” The disclosed structure for the means-plusfunction claims is thus “the special purpose computer programmed to perform the disclosed algorithm,” where the special purpose computer is disclosed in the specification as a computer or microprocessor programmed with the algorithm.

While “a listing of source code or a highly detailed description of the algorithm” is not required, the specification must at least disclose the algorithm that transforms the general purpose computer or microprocessor into the special purpose computer.

The Federal Circuit also explained that this requirement was not to be confused with the issue of whether the disclosure would enable one of ordinary skill in the art to make and use the invention, which is a different determination. The issue was limited to whether the means-plus-function claims were limited in scope to a particular structure and equivalents in order to comply with 35 U.S.C. 112, paragraph six.

Practice Tip: For computer related inventions using means-plus-function claim language, the specification should include at least a flowchart showing the algorithm or steps needed to achieve the function. Otherwise, the claim may be held indefinite as being purely functional language and, therefore, invalid.

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